Capturing of the rare Yanbaru whiskered bat

April 30, 2018

The critically endangered Yanbaru whiskered bat, Myotis yanbarensis, has been caught for the first time on Okinawa Island since its discovery 22 years ago. Kyoto University doctoral student Jason Preble succeeded in the capture on the night of 20 February, during a survey in the Yanbaru Forest in the north of Okinawa’s main island.

The rare bat species was first discovered in the subtropical Yanbaru Forest in 1996, when two specimens were collected. It was later observed on a few occasions on the islands Tokunoshima and Amami-Oshima, but no sightings were reported again on Okinawa Island.

This small tree-dwelling bat, endemic to these islands, thus became a serious conservation concern and was declared ‘critically endangered,’ the highest risk level, by both the Japanese Ministry of Environment and the International Union for the Conservation of Nature.

On 20 February 2018 at 20:05, Preble captured one male Myotis yanbarensis weighing 4.9 g and apparently in good health. Three nights later he caught a second male bat weighing 5.2 g. Upon release, he tracked these individuals using VHF transmitters. A third male was also caught four days later. The captures took place in the former United States military Northern Training Area, facilitated by a high-tech acoustic lure that broadcasts synthesized bat calls.

Moreover, Preble was able to record the bat’s echolocation call, vital data that was previously unreported.

This large area of forest was returned to Japan in December 2016, and Kyoto University’s Island Bat Research Group, led by Christian Vincenot, was among the first teams to be granted access by the Ministry of Environment, Okinawa Forestry Office, and Aha Dam authority.

The presence of the Yanbaru whiskered bat indicates that this zone, which was off limits for over a half-century, may have served as an unintended wildlife sanctuary. This discovery revives hope for conservation of this rare species, while also suggesting that Myotis yanbarensis may be range-restricted to a small part of the Yanbaru Forest and therefore may continue to be at risk of local extinction.

Extreme caution is therefore advised in the management of this area, which is currently a candidate for UNESCO Natural Heritage status. Bats are often highly sensitive to infrastructure development, as seen in the steep decline in endangered populations following the construction in 2013 of a new airport runway over bat caves on Ishigaki island, also in the Okinawan archipelago.